The present invention relates to a method for transmitting signaling information between an access point and a terminal of a multi-carrier radio communication network.
New generations transmission systems, such as 3-G or 4-G radio communication systems, need to transmit a lot of measures, metrics, commands or signaling information between the access points of the radio communication system and the mobile terminals. The load of these signaling information increases as the capacity of the transmission systems increases (more users, more available bandwidth . . . ).
Especially in multi-carriers system, a lot of information (measures, signaling, commands, metrics . . . ) for each sub-carrier are exchanged between the access point and the mobile terminal. Such multi-carrier transmission is provided in OFDM 2.4 GHz systems, in extensions of IEEE 802.11a HyperLAN2 system for example. In some systems, there can be up to thousands of sub-carriers. Usually, a certain amount of sub-carriers are used for transmitting the signaling information related to the traffic sub-carriers. The signaling information is represented in form of a signaling vector, the components of which indicate the signaling data for the different sub-carriers.
Bit loading techniques are usually employed to enhance multi-carrier systems. For each transmission time interval, a new state vector describing the distribution of the bits on the sub-carriers has to be sent to the receiver to that it can demodulate the signal using appropriate schemes for each sub-carrier. This has the consequence to increase quickly the signaling load since this state vector contains lots of data (for each sub-carrier, e.g. the modulation type, the transmitted power, the FEC).
Additionally to bit loading signaling, channel measures taken by mobile terminals and transmitted in the uplink up to the access point, or signaling information related to OFDMA are bandwidth consuming signaling which limit the amount of user data.
A particular object of the present invention is to find mechanisms that might significantly reduce the signaling load in a multi-carrier radio communication network.
Another object of the invention is to provide a terminal and an access point of a multi carrier radio communication network implementing these mechanisms.